Thursday 8 December 2011 06.39 EST
First published on Thursday 8 December 2011 06.39 EST

The death toll in Mexico's drug wars is a matter of intense controversy. The government released almost no official numbers until it published a database of all "deaths because of criminal rivalry" up to the end of 2010. These totalled 34,612, considerably more than the unofficial counts kept by several newspapers.

The government reneged on its promise to regularly update the database, although regional official figures are sometimes available.

One way of estimating the current total is by adding the official 2010 figure to this year's newspaper counts, making 46,000. Political scientist Eduardo Guerrero maintains his own count based on monitoring the press and factoring in estimated under-reporting to reach 47,500 by the end of October.

Some journalists and activists argue that the official criteria defining drug war deaths are too narrow and the real death toll is much higher.

The Tijuana-based magazine Zeta studied publicly available figures for all homicides. It identified classifications it said should be included to produce a figure of 50,490 until the end of July. This would suggest the current figure is approaching 60,000.

Who is dying is also in dispute. For the first three years of the offensive the government routinely claimed that 90% of those killed were linked to the cartels and most of the remainder were members of the security forces. This became increasingly difficult to sustain as evidence piled up of obviously unconnected people being killed.

From early 2010 the government switched to the claim that the vast majority of the killing was carried out by the cartels. This glosses over the issue of how many the security forces are killing. The newer focus is also a tacit admission that it is impossible to calculate the proportion of innocent victims because only a tiny fraction of all murders are properly investigated.

All calculations of the death toll ignore such phenomena as the habit of some organised criminal groups of retrieving their dead, and the practice of dissolving victims in caustic soda.

This year's discovery of mass graves also underlined the potential scale of the horror of large numbers of people going missing. The national commission of human rights said in April that 5,000 people had been reported missing since 2006.